Have you ever wondered why people get spammed by email? An obvious reason is that your email address is known by some spammer. But how? Junk ads (on paper) are easy -- just distribute an ad to each mail box by post. Phone calls are easy -- just get a phone directory and you will have millions of phone numbers. But how about email addresses? Spammers cannot try all combinations of email addresses as if every house/apartment or phone number. Even if all those electronic registrations on the web keep their promise and do not release your email to others, you can still get spammed.
Well, the answer is simple: you may have publicly released your email address on the Internet in some way, either by posting an article on a newsgroup, or putting your email address on your home page. Spammers, as time-wasters, of course would not waste their time reading all news articles and web pages themselves to look for email addresses, but they can write a program to search for email addresses.
You are now hired by a spammer to write such program.